A rotating disk viscometer has been developed aiming at measuring the viscosity at the critical consolute point of binary mixtures in the true hydrodynamic limit. The viscometer consists of a small magnetized disk set into slow rotation by a uniformly rotating magnetic field. The liquid is continuously sheared and no frequency effects should manifest even at the critical point. The phase delay between field and disk depends on the torques acting on the disk, including that of viscous nature. The viscosity can be calculated from the knowledge of the viscous torque obtained after calibration of the viscometer using literature data for ethanol. Preliminary testing results obtained with this novel apparatus are reported.